1. Field of the Invention
The present invention relates to a controller of a refrigerator having two evaporators.
2. Description of the Related Art
Among the recent refrigerators, there have been proposed ones having a refrigerating evaporator and a freezing evaporator to efficiently cool a refrigerator compartment and a freezer compartment, respectively.
In order to efficiently cool those two evaporators by refrigerant sent from one compressor, a three-way valve is disposed on the way of a passage of the refrigerant to decide to send the refrigerant to the refrigerating evaporator or the freezing evaporator by switching the three-way valve. In concrete, the following operation is carried by utilizing the three-way valve.
That is, a refrigerating mode of flowing the refrigerant to the both refrigerating evaporator and freezing evaporator and a freezing mode of flowing only to the freezing evaporator may be realized by switching the three-way valve. During the normal operation, an alternate cooling operation of conducting the freezing mode and the refrigerating mode is carried out.
In such a refrigerator, a defrosting operation has been conducted by actuating defrosting heaters provided in the vicinity of the evaporators after lowering compartment temperature by cooling the freezer compartment or the refrigerator compartment continuously for a certain period of time (this operation will be called a pre-cooling operation hereinafter) after when an accumulated operation time of the compressor has reached a preset time.
However, the defrosting operation described above has had the following problems.
Firstly, the refrigerator compartment is not cooled at all and the intra-compartment temperature of the refrigerator compartment rises during when the freezer compartment is continuously cooled by the alternate cooling operation described above and when the defrosting operation is conducted by means of the heater.
Secondly, when the normal alternate cooling operation is conducted after ending the defrosting operation, air warmed by the defrosting heater flows into the freezer compartment or the refrigerator compartment and hits against foods within the compartment, thus raising temperature of the foods.
Accordingly, in view of the problems described above, it is an object of the present invention to provide a refrigerator which is capable of suppressing the rise of the intra-compartment temperature during the defrosting operation by means of the defrosting heater and of preventing the temperature of the foods from rising after ending the defrosting operation.